Status of the PrimEx-eta Experiment in Hall D at Jefferson Lab

The η→γγ decay proceeds primarily via the chiral anomaly in QCD, and its decay width is useful for providing critical input to extract fundamental parameters of QCD, such as the η-η' mixing angle and the light quark mass ratio. Previous measurements of this decay width through e⁺e⁻ collider experiments differ from the result of the sole Primakoff experiment by more than 4σ. To address this discrepancy and to reduce the total uncertainty for the decay width, the PrimEx-eta fixed-target experiment in Hall D at Jefferson Lab (E12- 10-0111) is performing a precision measurement of the η→γγ decay width using the Primakoff method. The final part of the experimental data-taking for PrimEx-eta was just completed in Fall 2022. In this talk we will discuss the status of the experiment and the steps toward extracting the radiative decay width. Simultaneous with the η decay width measurement, the total cross section for Compton scattering off the atomic electrons is being measured. This well-understood QED process is used to verify the overall systematic uncertainties associated with a cross section measurment in the forward direction. In this talk we will also present the results for the integrated total Compton scattering cross section measurement.